Hot metal working lubricant



United States Patent Pennsylvania No Drawing. Filed Nov. 27, 1962, Ser. No. 240,442 4 Claims. (Cl. 252-28) This invention relates, as indicated, to an improved lubricating composition for the treatment and lubrication of surfaces subjected to conditions of extreme pressure and surface temperature such as encountered in the punching and piercing of hot metals, particularly ferrous metals.

Heretofore, piercing lubricants have generally been stable dispersions of graphite in hydrocarbon vehicle-s, usually a light parafiin distillate oil. In a conventional hot metal working operation, the metal to be formed is heated to a temperature of about 2,200 F. and is .then inserted in the die pot of a die press which has been preheated to a temperature of about 300800 F. Under these conditions, the hydrocarbon vehicle is flashed off and ignited on contact with the hot metal being shaped, thus creating a considerable amount of smoke and fire. Moreover, under these conditions, the vehicle is so quickly lost that inadequate and uneven coating of the graphite on the surface results, and poor lubrication of the hot metal-punch or die interface during metal working inevitably occurs.

The prior art has attempted to avoid the objections and hazards of smoke and fire by using water as a vehicle for the graphite. This has not been entirely satisfactory because of the even greater rapidity with which the vehicle is evaporated from the contacting surfaces. Thus the lubricant fails to adequately cover the surface and achieve bonding thereto.

In many instances, graphite is not satisfactory for lubricating purposes, and many different combinations including graphite have been produced in effort to enhance the lubricating properties of the composition.

The present invention overcomes the difliculties of the hydrocarbon and aqueous based compositions, and the difficulties of graphite containing compositions.

It has been found that very effective graphite-free metal working lubricants, especially in piercing operations, may be compounded from a clay grease composition containing or having dispersed therein a minor amount of a frit having a fusion temperature in the range of from about 750 F. to about 1,400 E, and a fusion flow temperature in the range of from about 900 F. to about l,550 F. To my knowledge, the combination of these two essential classes of ingredients has not heretofore been made, used or suggested.

Briefly stated, then, the present invention is in the provision of a lubricant, especially useful in the hot metal forming, such as piercing or punching, and consisting essentially of a clay grease and from about 5% to about 40% by weight of a finely divided low melting point glass frit. The fusion temperature is low in relation to silicon dioxide which melts in the range of from 1,600 to l,750 C., or from about 2,900 to about 3,200 F.

It becomes convenient, therefore, to discuss each of these essential ingredients individually, and then provide specific examples of compositions useful in accordance with the present invention.

CLAY GREASE Clay greases, and particularly the bentonite clay greases, are well known, and because of the relatively inert and stable character of the clays at elevated temperatures, greases formed therefrom are particularly use- 3A1 ,595 Patented Dec. 15, 1964 ful in accordance herewith. The clays utilized herein are preferably those classified as high base exchange clays, such as Wyoming bentonite, or hectorite; although clays of low base exchange capacity such as Georgia clay, attapulgite and the like may be utilized. The clay material is preferably chemically treated as by treatment with organic amines, ammonium compounds, quaternary ammonium compounds, etc., to enhance its ability to form a gel with a lubricant material, many such methods being known to those skilled in the art. The lubricant material may be of either the synthetic or natural type and includes mineral oil, and synthetic lubricating oils such as the polymerized olefins, phosphorus esters, silicon esters, and aliphatic esters formed by esterification of aliphatic, dicarboxylic acids with monohydric alcohols. Typical species of these materials include tricresyl phosphate, dioctyl phthalate, bis (Z-ethylhexyl) silicate, and the like. Other lubricants, particularly useful at elevated temperatures include the halocarbons and the organo-silico-n fluids. The halocarbons may be those described in Peterson et al. Patent 2,679,479, and include especially the fluorocarbon oils preferably distilling above about 200 C. at atmospheric pressure and the chlorofluorocarbons.

A most useful class of lubricants for grease compositions to be utilized at temperatures of the magnitude here involved include the organo-substituted silicon fluids of lubricating oil viscosity. Liquid organo-silicon polymers which are adapted for the preparation of the high temperature grease compositions may be obtained by the hydrolysis and chemical condensation of one or hydrolyzable silicon compounds having the general formula R SiX wherein R is a lower alkyl radical and X is a hydrolyzable group selected from the class consisting of halogen and alkoxy groups. They may also be obtained from the hydrolysis and chemical condensation of a mixture of alkylated silicon compounds containing at least mol percent of such dialkyl silicon compound having the formula R SiX and not more than 25 mol percent of a monoalkyl silicon compound having the formula RSiX or a total of not more than 25 mol percent of both such monoalkyl silicon compound and a trialkyl silicon compound having the formula RgSiX. In all of these formulae R and X have the meanings stated above.

Examples of hydrolyzable dialkyl silicon compounds which may be used in preparing the liquid organo-silicon polymers are dimethyl silicon dichlorde, methyl ethyl silicon dichloride, methyl propyl silicon dichloride, dimethyl silicon dibromide, dimethyl-dimethoxy-silicon, diethyl-diethoxy-silicon, dimethyl-diethoXy-silicon, etc. Examples of hyldrolyzable monoalkyl silicon compounds and hydrolyzable trialkyl silicon compounds which may be present together with the dialkyl silicon compound in amount not exceeding 25 mol percent of the mixture of methyl silicon trichloride, ethyl silicon tribromide, ethyl silicon trichloride, propyl silicon trichloride, methyl-trimethoxy-silicon, methyl triethoxy silicon, ethyl-triethoxysilicon, trimethyl silicon chloride, trimethyl silicon bromide, triethyl silicon chloride, trimethyl-methoxy-silicon, trimethyl-ethoxy-silicon, triethyl-ethoxy silicon, etc.

The liquid organo-silicon polymer may be obtained by heating the hydrolyzable silicon compound or compounds with water in the presence of a hydrolysis catalyst, e.g., a mineral acid. Hydrolysis of the silicon compounds to form corresponding organo-silicols (which silicols are unstable under the reaction conditions and in some instances have not been isolated as such) is accompanied by chemical condensation of the silicols to formthe liquid organosilicon polymer (or copolymer) product. The starting materials are selected so that the product contains an average of between 1.75 and 4, and preferably between 1.9 and 2.5 atoms of carbon per atom of silicon. The liquid polymers having viscosities exceeding 500 Saybolt seconds at 100 F. are preferred in preparing the clay greases useful in accordance herewith. Further details concerning the silicon type greases may be found by having reference to Patent No. 2,886,524 dated May 12, 1959.

A clay grease prepared from mineral oil is disclosed in Patent No. 2,831,809 dated April 22, 1958. Patent No. 2,766,209 dated October 9, 1956, Patent No. 2,531,440 and Patent No. 2,623,873 all teach various types of clay greases which may be used in accordance with the present invention.

The clay or bentonite greases of the present invention are characterized by the fact that they have no fixed melting point. The grease coacts with a glass frit to hold the latter in place on any contour regardless of the temperature. Under hot metal forming conditions, the greases, and particularly the silicon greases, coact very Well to distribute the frit material quite uniformly over the surface of the die, and because of its resistance to flow at such elevated temperatures, vertical die portions do not become starved for lubricant due to run off. The grease composition comprises from about 60 to about 95 percent by weight of the entire lubricant composition.

THE FRIT COMPONENT The frits useful in accordance with the present invention are generally finely divided ground glass compositions which in general are mixtures of metal oxides having a melting point or frit fusion temperature in the range of from about 750 F. to about 1,400 F. These frits flow at temperatures of about 150 F. higher than the fusion temperature. The particle size of the frit is not critical, but for practical purposes ranges from about 50 to about 325 mesh or finer, a convenient particle size being a frit of which 95 percent will pass through a 200 mesh standard screen.

Under the conditions of piercing temperatures are sufficiently elevated, i.e. in the range from about '1,600 F. to about 2,500 F., that all organic material is destroyed or vaporized, and the remaining relatively low melting point glass frit-clay residue then serves to prevent metal-to-metal contact and seizure between the piercing tool and the pierced member. The frit constitutes from about 5% to about 40% by weight of the entire composition.

Low melting frits are also well known in the art. For example, reference may be had to Patent No. 2,800,414 for a frit which matures at about 1,100 F. Another low melting frit composition which may be used in accordance with the present invention is described in Patent No. 2,827,393. Still other frits which may be used in the compositions of the present invention are those which are described in Patent No. 2,925,351.

These frits are characterized in that they are insoluble in hot metal, nonoxidizable, and are viscous fluids at temperatures of forging and forming of metals which aids in their adhesion to the surface and a prevention of seizure and galling.

The frit may be lead-free or lead-containing. Suitable examples of lead-free frit compositions drying and firing in the range of 940-1,040 F. will be found in Patent No. 2,927,393 dated March 18, 1958. These compositions have analyses within the following ranges for the indicated ingredients.

The sum total of the foregoing oxides is in the range of to 25%. Non-refractory glassmakers:

Percent The sum total of the foregoing oxides is in the range of 10% to 55% Refractory glassformers:

Percent PbO 0-90 A1 0 -2 0-25 S10 0-25 ZIOZ 0- 5 TiO 0-10 The sum total of the foregoing oxides is in the range of from 20% to Typical examples of frits within the foregoing composition ranges are as follows:

EXAMPLE I Percent Na O 7.0 B 0 14.0 PbO 60.0

SiO 19.0

fused, quenched and ground to through 200 mesh screen.

EXAMPLE II Percent Na 0 3.0 K 0 3.5 B 0 10.5 P 0 4.0 PbO 60.0 SiO 19.0

fused, quenched and ground to 95 through 200 mesh screen.

EXAMPLE III Percent Na O 22.0 Li O 3.5 B 0 7.0 P 0 43.5 MP 4.0 A1 0 20 0 fused, quenched and ground to 95% through 200 mesh SCIIL EXAMPLE IV Percent B 0 20.0 PbO 80.0

fused, quenched and ground to 95 through 200 mesh screen.

EXAMPLE V Percent B 0 10.0 PbO 88.0

SiO 2.0

LiO 5-15%. BaO 31-10%. B 0 5-10%. A1 0 0-15%. (PO )P O 5-15%. SiO 525%. CaO, K 0, Na O, TiO and/ or ZrO Balance.

Numerous other examples of frits will thus become readily apparent to those skilled in the art. The ingredients from which frits useful in accordance herewith are made may be supplied from a variety of sources. For example, in preparing the batch for making the frit, sodium oxide may be introduced thereto as borax, sodium nitrate, sodium carbonate, sodium silicate, feldspar, etc. calcium oxide as calcium fluoride, calcium carbonate, etc.; boron oxide as borax, either hydrated or not, boric acid, colcmanite, razorite, etc.; silica as flint, feldspar, sodium silicate, etc.; titanium dioxide as rutile, titanium hydrate, alkali metal titanates, etc.; lead oxide as white lead, red lead, lead silicate, litharge, etc.; fluorine as sodium fluoride, sodium silical fluoride, calcium fluoride, sodium aluminum fluoride, etc.

PIERCING LUBRICANTS The lubricants of the present invention are formed by dispersing in one of the foregoing clay greases or a mixture of two or more such greases from about 5% to about 40% by weight of one of the foregoing frit compositions. It has been found that for most purposes, percent by weight of the frit dispersed in 90 percent by Weight of a clay grease produces a very satisfactory piercing lubricant. The dispersion of the frit in the grease is very easily accomplished by introducing the ingredients to a conventional grease mixing apparatus or a Werner- Pfleiderer mixing machine.

It becomes convenient at this point to illustrate the lubricating compositions of the present invention by giving specific examples thereof, it being understood that these examples are by Way of illustration and not by way of limitation. Moreover, these examples illustrate compositions comprising the essential ingredients described herein, it being also further understood that the inclusion of other ingredients is not precluded by these examples so long as the additional ingredients do not adversely affect the compositions for the intended purposes. The term consisting essentially as applied to these compositions is intendcd to mean, therefore, that these compositions include the specific ingredients mentioned as well as other ingredients in amounts which will not adversely affect the composition for the intended purposes i.e. forming of metals at elevated temperatures.

EXAMPLE VI Parts by Weight Bentonite grease 9 Hydrophobic, oleophilic modified montmorillonite,

Mid-Continent bright stock VF 150 oil, 85%. Frit (Example I) 1 EXAMPLE VII Bentonite grease 4 Frit (Example III) 1 EXAMPLE IX Bentonite grease 5 Bentone 18 (18 C-amine modified bentonite clay),

30%. Mineral oil, bright stock, 70%. Frit (Example IV) 1 0 EXAMPLE X Bentonite grease 9 (See Example VI.) Frit (Example V) 1 EXAMPLE XI Hectorite silicone grease 9 Aniline coated clay, 66%. Silicone fluid (Dow Corning fluid 550) (See US. a

Patent 2,886,524, Example I), 34%. Frit (Example I) 1 remarkable, tool life is improved, and separation of the tool from the metal is very easy. No problems of adverse chemical eifect upon the metal skin have been observed in the use of these compositions.

Qther modes of applying the principle of this invention may be employed instead of those specifically set forth above, changes being made as regards the details herein disclosed, provided the elements set forth in any of the following claims, or the equivalent of such be employed.

It is, therefore, particularly pointed out and distinctly claimed as the invention:

1. A hot metal working lubricating composition especially adapted for use in working solid metal at a temperature above 750 F. but below the melting point of the metal consisting essentially of from about 95% to about 60% by weight of a clay grease, and from about 5% to about by weight of a low fusion point frit in finely divided form and intimately admixed therewith, said frit having a fusion point in the range of from about 750 F. to about 1,400 P.

2. A hot metal Working lubricant in accordance with claim 1 in which the frit has a fusion point in the range of from about 750 F. to about 1,100 F.

3. A hot metal working lubricant in accordance with claim 1 in which'the frit has a particle size in the range of from about to 325 mesh.

4. The method of forming a solid body of hot metal at a temperature in the range of from above about 750 F. to just below the fusion point of the metal in a die which comprises the step of interposing at the interface between the metal being pierced and the tool, a lubricant composition consisting essentially of from about 95% to'about by weight of a clay grease, and from about 5% to about 40% by weight of a low fusion point frit in finely divided form and intimately admixed therewith, said frit having a fusion point in the range of from about 750 F. to about 1,400 F.

References Cited by the Examiner UNITED STATES PATENTS 2,900,338 8/59 Postelnek 25228 2,920,042 1/60 Eastman 25228 3,059,769 10/62 Frost 252-28 DANIEL E. WYMAN, Primary Examiner. 

1. A HOT METAL WORKING LUBRICATING COMPOSITION ESPECIALLY ADAPTED FOR USE IN WORKING SOLID METAL AT A TEMPERATURE ABOVE 750*F. BUT BELOW THE MELDING POINT OF THE METAL CONSISTING ESSENTIALLY OF FROM ABOUT 95% TO ABOUT 60% BY WEIGHT OF A CLAY GREASE, AND FROM ABOUT 5% TO ABOUT 40% BY WEIGHT OF A LOW FUSION POINT FRIT IN FINELY DIVIDED FORM AND INTIMATELY ADMIXED THEREWITH, SAID FRIT HAVING A FUSION POINT IN THE RANGE OF FROM ABOUT 750*F. TO ABOUT 1,400*F. 